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Hot DOG surprise reveals new stage in galaxy evolution

5 September 2012

THIS frankfurter won’t fit on a bun. Newly discovered hot dust-obscured galaxies, or hot DOGs, could help explain how a galaxy’s evolution is influenced by the black hole at its core.

Though 1000 times brighter than the Milky Way, these dusty galaxies went unseen until a team led by Jingwen Wu of NASA’s Jet Propulsion Laboratory in Pasadena, California, observed their infrared radiation.

The team used this to calculate the mass of the hot DOGs’ central black holes, which are heavier relative to the surrounding stars than black holes in an ordinary galaxy (Astrophysical Journal, doi.org/h8g). The team says all galaxies may go through a hot DOG stage as they evolve. Once the black hole has eaten or ejected all the nearby dust and stopped growing, ongoing star formation eventually turns the hot DOG into a normal galaxy.